Demand for data storage capacity has increased substantially as the use of data intensive applications has grown more common. Internet use and data-intensive applications such as multimedia and online transaction processes have contributed to the increased demand for data storage capacity. Users are also demanding faster access to the data and the ability to share pooled data among a large number of users over distributed locations. To meet demands for increased storage capacity and more rapid access to data, the computer industry is turning to storage area networks (SANs), collections of data storage devices interfaced with one or more servers or workstations. Many SANs make use of Fibre Channel (FC) technology for transmitting data at higher rates. FC devices are often based on Fibre Channel Protocol (FCP) which may also be referred to as the Fibre Channel standard. FCP supports a number of protocols including SCSI, Asynchronous Transfer Mode, Transmission Control Protocol/Internet Protocol (TCP/IP), High Performance Parallel Interface (HiPPI), Intelligent Peripheral Interface (IPI) and others.
FCP requires that each node and its associated ports in a Fibre Channel network have unique addresses known as Worldwide Names. Each Worldwide Name contains eight bytes (64 bits). Three bytes (twenty-four bits) are used to identify the manufacturer of the device and are assigned to registered members by the Institute of Electrical and Electronics Engineers (IEEE). Another three bytes define the vendor specified field and are used by each vendor to create a unique identifier for the devices. The remaining two bytes may also be used by the manufacturer to extend the vendor specified field.
Although each Worldwide Name contains eight bytes of information, manufacturers may only the vendor specified field to define unique addresses for their devices. Once the manufacturer exhausts all of the possible combinations in the vendor specified field, the manufacturer must be assigned a new company identification number by the IEEE. Manufacturers are required to manage their assignment of identification numbers to insure that duplicate addresses are not assigned. Because FCP allows for a longer address field, existing systems used to manage the assignment of identifiers for MAC addresses will not allow for the management of assigned identifiers for FCP devices. Consequently, managing the identifiers of FC devices typically requires establishing an additional system to keep track of the assignment of identifiers for those devices.
Another difficulty associated with the assignment of WWNs is that if a manufacturer switches from assigning MAC addresses to WWNs, the manufacturing process requires modification to incorporate the WWN since the worldwide name is typically stored in non-volatile memory such that the WWN is saved when a system is turned off or power is lost.
Another difficulty with assigning WWNs to fibre channel devices is the need to include additional non-volatile random access memory (NVRAM) on either the device itself or the motherboard of a server that the device couples to. Because NVPAM is typically expensive, the need for additional NVRAM for storage WWNs increases the overall cost of the system.